4 cable method ή τελικός+καμπίνα?

[The Genius Loci]

 

Σχετικά με το FRFR παραθέτω ένα post-άρθρο από το Fractal forum:

 

I'm drafting this post in an effort to provide answers to the most common questions about FRFR systems.

 

Q. What is FRFR?

A. "Full Range Flat Response." Both halves of the expression are approximations. Technically speaking, "full range" means the entire audible bandwidth of 20Hz - 20kHz. Practically, for use with electric guitar, it means the bandwidth of electric guitar, including all harmonics added by the amp. That range is approximately 80Hz- 8kHz for standard tuning. Dropped tunings nominally require more low frequency bandwidth. "Flat response" is never perfectly achieved in any loudspeaker. However, the better designs can approach flatness over a reasonable bandwidth within plus or minus 2dB.

 

Q. Are guitar cabs FRFR?

A. No, far from it. In fact the nonideal behavior (i.e., frequency response with substantial notches and peaks) of guitar speakers and cabs is a desirable part of the sonic signature of an amp.

 

Q. Then why would I want to use an FRFR speaker with the Axe-Fx?

A. Because the Axe-Fx has cabinet simulation. If you use cab sims, the sonic signature of the cab represented by the chosen sim is applied to the signal in the Axe-Fx. No further coloration from the speaker is required to produce the effect of the cab. In fact, added colorations (e.g., playing through a guitar cab with cab sims on) can obscure the character of the speaker sim you've chosen.

 

Q. What is the difference between studio monitors and, say, a keyboard amp?

A. Studio monitors are represented as references. To the extent that the representation is accurate - not a given - a monitor will have flat response and be relatively full range. To do their job well, monitors only need to be able to produce this optimum response in a very small space, because the expected number of listeners is small, and their positions will be as close as possible to the stereo "sweet spot." Really good studio monitors are quite expensive, and getting good results from them requires a lot more than just setting them up in a room and connecting cables to them.

 

Like studio monitors, keyboard amps and PA speakers (also called "sound reinforcement, or "SR" speakers) in general are represented as being relatively full range. Unlike monitors, SR speakers are generally expected to provide sound for many listeners situated over a relatively wide area. On average, SR speakers are required to produce higher acoustic output than studio monitors, although there are certainly studio monitors that can get loud enough for SR. The demand on acoustic output, combined with pressure to keep prices as low as possible, leads many manufacturers of SR speakers to make significant compromises in the response and directional behavior of their products. For this reason, "FRFR" speakers designed for SR use vary widely in performance, and caution is warranted in choosing which one to use with an Axe-Fx.

 

More added from PMs:

 

Q: How does the sound dispersion "on stage" compare between a FRFR and a conventional speaker cabinet, say a 4X12?

A: The number of transducers and their relative positions are a major factor in the directivity of a loudspeaker. An SR speaker will reliably have broader directivity ("dispersion" has a technical meaning unrelated to directivity) than any 4x12 cab. A 4x12 cabinet is highly directional for two reasons: the 12" transducers become very directional on their own above about 1200 Hz, and the 2x2 array of transducers itself is directional and would be so even if the individual transducers were not.

 

Q: Does an SR system have a "sweet spot"?

A: Many do, although the ideal example would have a very broad "sweet spot" such that all listeners would be well within it. However, in almost every case, the "sweet spot" of an SR speaker is larger than the "sweet spot" of a guitar cab.

 

Q: Why does a "real" guitar cabinet feel more "in the room" than an FRFR that is modelling that cabinet?

A: The inclusion of the word "why" implies that this is always or necessarily the case. In my experience, it is not. A better question might be "How do I make an FRFR speaker sound more like a "real" guitar cab?"

 

Q: Does the number of speakers in an FRFR system have any relevance to the number of speakers in the cabinet that the FRFR system is replicating (i.e. the IR that it is reproducing)?

A: Only in a peripheral way. If the IR you're using was taken with the mic in a position that is representative of your location while playing, and if the FRFR speaker you're using is sufficiently neutral, you can recreate the sound and feel of a 4x12 cabinet with an FRFR speaker that employers fewer than four transducers.

 

Q: Can I replace the 12" speakers in a guitar cabinet with FRFR speakers?

A: If you are a loudspeaker designer, you might stand a chance of pulling off this kind of modification. No 12" transducer is FRFR by itself. There has to be a tweeter (and therefore a crossover) as well.

 

http://www.fractalaudio.com/forum/viewtopic.php?f=13&t=4443

 

Νομίζω ότι απαντάει τις απορίες.